In reply to dale1968:
Because:
a) Little useful evidence has come to light a year on
b) People will believe what they want to believe. Anything deemed to be "evidence" will be discredited by those it doesn't suit, and their supporters will believe their version of events.
c) I can't see anyone ever standing trial for it.
FWIW, I think it was downed by Russian-backed separatists using Russian weapons, but there is so much smoke and mirrors it's impossible to know the truth about it, or indeed the whole situation in Ukraine in my opinion.